The present invention relates to a system of mechanical components arranged to cooperate with each other for locking and unlocking a rotatable screen that is located for intercepting the flow of fluid through a channel such as a catch basin curb inlet channel. More particularly, the present invention relates to such a system that holds the screen closed to impede the movement of fluid-borne trash under low fluid-flow conditions but automatically releases the hold for allowing the screen to rotate open in order to permit an increased volume of the fluid (and trash carried with it) to move downstream past the screen during high fluid-flow conditions, and then automatically resumes its hold when the screen re-closes upon dissipation of the high fluid-flow conditions.
As used herein (“herein” being inclusive of this specification, including its claims, and accompanying drawings), “screen” includes any physical device having apertures for allowing fluid to pass through the device while blocking such passage of at least some trash. Examples of said devices, which may differ in part based on the size of their apertures, include screens, filters, sieves, grids, grates, and gates.
As used herein, “trash,” means any item of natural or man-made solid material, including any comprised of trash, debris, vegetation, one or more sticks, one or more rocks, all or part of an animal, or any combination thereof, that is large enough to be blocked by the screen, as determined by the size(s) of the openings in the screen. And, “trash” is used as a reference to such items sometimes singly and sometimes plurally as indicated by the context. Of course, any given screen may be unable to block some items of trash with a dimension larger than the screen's openings, particularly where those items are elongated, compressible, and/or flexible enough to sometimes pass through the openings.
As used herein, “channel” means any inlet, catch basin, channel, conduit, pipe, culvert, tube or any other man-made or natural confinement, or any system comprising some or all of these elements, through which fluid flows on at least some occasions. Channels, particularly drainage channels, often include a catch basin. The catch basin is typically located near the channel's beginning point; that is, near the point at which fluid first enters the channel system.
As used herein, “fluid” means any fluid, or combination of fluids, that is normally or reasonably expected to be carried by the channel in which an automatic screen fluid channel lock-unlock system, as described and/or shown herein, is installed.
Trash tends to be moved by fluid and thereby enter into channels that collect or direct the flow of the fluid. It is generally desirable to minimize the amount of trash in the channel, particularly items of trash that are too large for the channel to move throughout its length during light or moderate flow periods or that are large enough to create an environmental, aesthetic, health, or other problem, such as an obstruction or a build up, near the discharge end of the channel. On the other hand, it is desirable for channels to be available for receiving and moving large amounts of fluid during heavy flow periods. The need for these desirable features is particularly apparent when considered in the context of a street or highway storm drain system.
Streets and highways frequently have curb inlets leading to catch basins as the initial entry points of drainage systems for collecting and draining water and other fluids that would otherwise accumulate in and ultimately flood the street or highway. It is desirable to minimize the entry of solid materials that are larger than a relatively small size, in order to reduce the frequency needed for cleaning such materials out of the system, and to reduce the potential for animals or even small children entering through the inlets.
It may be observed that many curb inlets have no effective means for blocking the entry of trash. There have been ideas put forward that involve installation of a trash blocking device at the inlet but typically those devices require manual cleaning or removal to relieve the damming effect of an accumulation of trash during periods of heavy fluid flow. (See, e.g., U.S. Pat. No. 4,986,693, issued to Salberg et al. on Jan. 22, 1991; U.S. Pat. No. 5,702,595, issued to Mossburg, Jr. on Dec. 30, 1997; U.S. Pat. No. 6,017,166, issued to Mossburg, Jr. on Jan. 25, 2000; and, U.S. Pat. No. 6,402,942, issued to Cardwell et al. on Jun. 11, 2002.) Of course, during light flow periods, when the amount of accumulated trash at the entrance is relatively small and does not significantly impede the flow of fluid into the drainage system, street and highway maintenance personnel have no immediate need to clear the curb inlets and are at liberty to do so according to a schedule without significant risk of a flood occurring.
However, during periods of heavy flow, due to storms or other events that produce substantial amounts of fluid in the streets and highways, it is imperative that any significant impediment to the flow of such fluid into the drainage system be removed. These heavy flow periods often commence unexpectedly or on very short notice and, in some geographical areas, frequently. Thus, installation of most previously proposed blocking devices for curb inlet channels would put maintenance personnel under extreme pressure to mount an intensive and expensive effort to remove the blocking devices whenever heavy flow periods occur. Removal of such blocking devices generally requires personnel to expend substantial time and, in some cases, to use expensive equipment in order to access and remove the connecting means and the devices.
Nevertheless, such removal is necessary because the trash accumulated at the face of the blocking devices significantly impedes the large volume of fluid that is flowing into the drain system, thus causing a damming effect. Also, the blocking devices will continue to block and accumulate the additional trash that is being carried with the large volume of fluid, exacerbating the damming effect. Therefore, unless agencies that have responsibility for street and highway maintenance and/or flood control either forgo the benefits of having blocking devices or expend large sums for personnel and equipment to immediately remove the blocking devices every time a heavy flow period threatens or commences, the accumulations at the entrances to their drainage systems are very likely to cause substantial flooding.
It has been suggested that a blocking device made of elastic plastic material is needed to overcome the prohibitive cost, weight, and installation difficulties, found in blocking devices made of metal or other non-plastic material. And, further, that the prior devices made of metal or other non-plastic material are not particularly suitable for installation within a curb inlet channel and generally do not, without human assistance, clear the accumulated trash during periods of heavy flow. It has also been contended that attaching the heavy components of metal blocking devices with bolts anchored within the inlet or catch basin will weaken and over-stress that structure. (See U.S. Pat. No. 6,015,489, issued to Allen et al. on Jan. 18, 2000, which discloses a plastic self-relieving curb inlet filter that is secured by adhesive along its top edge within the curb inlet and is sufficiently elastic to flex open in response to increasing pressure and unflex toward its closed position as the pressure is reduced.) Such a device offers advantages that may be achieved from the use of plastic and adhesive materials. However, the advantages also appear to be limited by those materials. The strength, flexibility and elasticity of plastics and adhesives may be adversely affected by repeated flexing and extended exposure to environmental conditions such as sun, air, water, and extreme temperature variations (ranging from above 100 degrees Fahrenheit to well below 0 degrees Fahrenheit in some geographical areas). A secure bond may be difficult to achieve or maintain in circumstances where the surface (generally made of concrete) suffers from irregularities, impurities, or mechanical weaknesses; and, if achieved, may be difficult to remove without some damage to the surface or the device. And, the efficacy of the device in opening and closing is dependent on the elasticity of the material used. Thus, if a very elastic material is used, the device may open with little pressure applied, such as during periods of light to medium fluid flow when remaining closed is generally desired. And, if a very inelastic material is used, the device may not open fully even when the initial resistance is overcome by a large pressure (the degree of resistance in such materials often increasing with the degree of flexure), which is generally when full opening is most desired. Such a device, therefore, provides no effective means of control to assure the blockage is maintained when that is most desirable and released when that is most desirable.
Consequently, as indicated above, it appears that some of the prior efforts at blocking the passage of trash in channels, and particularly in catch-basin curb inlets, were directed primarily either at the use of rigid heavy materials for devices that were expensive and difficult to install and remove, or at use of elastic plastic material for making a device that would open and close in response to the pressure caused by a high level of fluid and accumulated trash. It also appears that those efforts did not address or suggest a practical and economical solution to the problem of trash accumulation and blockage during heavy flow periods when the passage of fluid needs to be maximized. However, that problem was addressed by suggesting the use of relatively light metal components that include a rotatable grid positioned in the inlet channel (e.g., by the grid being connected to a rod running proximate the grid's upper edge with the rod connected to a support on either end; and, include a hold and release means that employs one or more magnets (which could be replaced by, or combined with, other hold-release means, such as a latch or other mechanical gripping device (which generally require that one part of the device be connected to the grid's support and another part be connected to the grid), provided the other hold-release means is suitable for the channel environment and has characteristics substantially similar to magnets of equal pull limit, with regard to the ability to hold the grid, to automatically release the grid when pressure against its front overcomes the holding ability (referred to as pull limit in regard to a magnet) of the magnets and/or other hold-release means, to then automatically resume holding the grid, and to repeat such cycle as often as deemed necessary by the user. See, U.S. patent application Ser. No. 10/794,664 filed by Nino, published on Sep. 9, 2004, as #US20040173513. And, an approach has been presented in which an upwardly biased trip plate is rotatably attached by its forward edge to the rear of a rotatable catch basin inlet gate, the bias urging the plate into a perpendicular relationship with the closed (vertically oriented) gate, the plate having a pin extending laterally from each side, proximate the rear of the plate, to engage another part that prevents rearward movement of the pins (thus, of the plate and gate), until the weight (or action) of fluid on the plate overcomes the upward bias and the plate rotates downward (its rear edge, and the pins, moving downward), which allows the gate to rotate rearward and open. See, e.g., U.S. Pat. No. 7,234,894 issued (from application Ser. No. 11/335,591) to Flury on Jun. 26, 2007; and, U.S. patent application Ser. No. 11/821,623 file by Flury on Jun. 25, 2007, published on Jan. 17, 2008, as #US2008/0014021 (a continuation-in-part of U.S. application Ser. No. 11/335,591). And, there has been a proposal for a use of a water wheel coupled via a cable, pull rod, etc. to a rotatable gate for opening the gate in response to fluid causing the water wheel to rotate and pull on the cable. See, e.g., U.S. Pat. No. 6,972,088 issued to Yehuda on Dec. 6, 2005.
It is believed that the present invention provides a mechanical system for locking and unlocking a rotatable screen in a fluid channel that offers advantages over and/or desirable alternatives to the prior art relating to control over the opening and/or closing of such a screen.